Automatic alarm selector



Oct. 5, 1937. F. BYRNES 2,094,733

AUTOMATI C ALARM SELECTOR (fw/mf 12 maf/fr HAY . L+ /A//Jz/f j [lum-D ihm INVENTOR BYRNES ATTORNEY Oct. 5, 1937. l. F. BYRNES AUTOMATIC ALARM SELECTOR -Filed lay 25, 1933 2 Sheets-Sheet 2 Patented Oct. 5, 1931 AUTOMATIC ALARM SELECTOR Irving Francis Byrnes, Riverdale, N. Y., assignor to Radio Corporation -ot tion of Delaware erica, a corpora- Application May z5, 1933, serial No. 672,778 loclaims. (01477-353) This invention is concerned with an automatic alarm selector circuit for giving an alarm on the receipt of a predetermined wireless signal composedof a regular series of dashes of definite lengthand spacing such as is used for requesting aid by ships at sea. In the present case the signal under consideration consists, by international agreement, of a pluralityof dashes oi' four seconds duration separated by spaces of one second l0 each.

Since the signal necessary to operate the alarm is frequently sent by hand, and the timing done by the aid of a watch, it is essential for the eilec'- tive operation of the system that some tolerance be permitted in the length oi' the dashes and spaces so as to allow for errors in sending. 'Ihe present invention is, therefore, designed to respond to dashes of from between three and onehalf to four and one-half seconds duration and to spaces of less than one and one-half seconds,

and this is accomplished by suitable choice of voltage, resistance and condenser values, together with proper adjustment of spring tension in the relay mechanisms employed. This latitude allows for an error .of plus or minus one-half second in the length of each dash, a tolerance which, it has been found in practice, is suilicient for hand operating. Although this particular degree of latitude due to signal variation is preferred, it

will be understood, of course, that the permissible amount of deviation from exact signal length may be changed merely by the change in values of the elements indicated above. i

Heretofore, the systems which have been pro- .15 posed have been based largely on the use of mechanically driven cams with clutch mechanisms arranged to be driven at constant speed by motors.

Other known systems utilize dash-pot relays consisting of small pistons working in suitable cylinders for securing timing. These prior art arrangements, however, suier from certain disadvantages such as being diicult to build and, when constructed, diillcult to maintain in adjustment.

It has been found that the wear and tear on such mechanical alarm systems reduces the life of the parts to a considerable extent.

The present invention, on the other hand, overcomes the aforementioned disadvantages by providing a selector system which has its timing based on an electrostatic arrangement rather than on a mechanical circuit scheme. According to the proposed arrangement, the only moving part during telegraphic reception is the armature of the radio relay.

55 One feature of this invention is the time-constant resistance reactance circuit which functions to time the operation of various relay devices through the medium of a thermionic electron discharge device. This circuit may comprise the combination of a resistance with either an in- 5 ductance or a condenser, although the use of the condenser combination is preferred.

Other features and advantages will appear in the following detailed description which is accompanied by drawings wherein Figure 1 illustrates 10 one embodiment of the present invention, Figure 2 the preferred selector arrangement, and Figure 3 a modified time constant resistance inductance circuit which may be used in either cf the circuits of Figures 1 and 2. 15

In Figure 1 there is shown an automatic alarm selector comprising, essentially, a signaling relay I which is connected to an input circuit 2 associated with any suitable radio receiving apparatus, not shown, through the medium of an elec- 20 tron discharge device 3. Associated with relay I there are a plurality of relays I, 5 and B having individual to themselves thermlonic devices l,

8 and 9, respectively, for causing the actuation of a stepping magnet I0 and a restoring magnet 25 II, the latter two magnets, in turn, controlling the operation of an alarm device I2. Relays I,

I, 5 and 6 are of the quick acting type for conditioning the circuit for operation immediately upon the receipt of signal characters. 30

Electron discharge device 8 is normally biased by grid battery I3 so as not to pass any current which might be suillcient to close relay 5 when no signals are being received, and to pass current only upon the building up of a potential charge on condenser C1, due to the operation of relay I, of a value sutlicient to overcome the eiiect of the biasing battery. Relay 5, which is in the anode circuit of device 8, is arranged to operate after a period of three and one-half seconds from the time con- 40 denser C1 starts to charge, during which time it is assumed that the charging current is continuously applied to the condenser. The timing of this relay is affected by several factors which include primarily the capacity of condenser C1, the value of resistor R1, and the value of the source of voltage supply ZI in circuit with resistor R1.

Relay 4 is controlled through thermionic device 1 in a somewhat similar manner to operate in four and one-half seconds after the application of potential to condenser C: dueto the operation oi.' relay I and, similarly, relay 6 is arranged to operate at the end of five seconds after the continuous application of a charge on condenser Ca.

Stepping magnet Ill'functions to move its arma- 5" ture one notch each'time upon the operation of relay E, until after three successive operations oi this relay a circuit is closed to energize an indicator of anydesired type, such as a bell I2.

A restoring relay il is provided to return the stepping magnet to its normal position.

In the operation of the circuit, a radio signal, after being detected and amplied at an audio frequency in the usual manner of the receiver, not shown, is impressed on the grid filament circuit of'electron discharge device 3 over input circuit 2. This tube is biased to cause the operation of signal relay i located in its anode circuit immediately upon receipt of a signal, relay l, in turn, acting to open the circuits of break contacts i5 and I6 and to close those of make contacts i4 and I1. The circuit shown in the drawings illustrates the normal condition of the selector when no signal is being received.

The operation of signal relay i closes a circuit to energize condenser C1 through resistor R1 and contact Il. The charge on this condenser `functions to overc'ome the bias of battery |3 on relay tube 8 so as to permit the operation of relay 5 in the anode circuit of the tube, a matter which occurs at the end of three and one-half seconds during which time the charge on the condenser C1 has increased to such a value that the desired amount of anode current flows through the tube. Relay 5, in turn, operates to close its make contacts i8 and I9 and to complete a path for the operation of stepping magnet |0 over its right hand armature and contact I9. The operation of stepping magnet i0 causes its armature to move forward one step or notch. The closure of make contact i8 providesl a shunt path around condenser C3 for the purpose of keeping this condenser discharged.

If at any time theincoming signal ceases, relays i and 5 will return to normal and contact i8 will open, thus enabling condensers C1 and C2 to discharge and a charge to be built up on condenser Ca. 'I'he circuit for Ca may be traced over a path from the left hand plate of the condenser through lead 20 to the negative side of source 2|, and from the right hand plate of the condenser over the left uter normally made break contact of relay 5 through resistance R3 to the positive terminal of source 2|. After ve seconds there will be suflicient charge on condenser C3 to overcome the biasing battery connected to the grid of tube 9 and to enable relay 6 to operate and close an obvious circuit for the energization of restoring magnet If", however, instead of the radio signal ceasing, it should last for more than four and one-half seconds, there will be placed a charge on condenser Cz by source 2| over a circuit traced through resistance Rz and make contact lll of signal relay which will completely overcome the opposing biasing battery of tube 1 and enable relay 4 to operate and thus energize restoring magnet l i over a very obvious circuit. 'I'he receipt of three correct dashes and three correct spaces will cause stepping magnet |0 to move its armature three notches forward and thus close a circuit to operate the alarm |2.

From the foregoing, it will be evident that the stepping magnet It functions to provide an alarm only when the incoming signal consists of dashes over three and one-half seconds and under four and one-half seconds separated by spaces under one and one-half seconds, otherwise either relays 4 or 6 will operate to restore thecircuit to normal. The spaces it will be noted may be any short interval under one and one-half seconds.

Figure 2 shows a preferred' arrangement wherein only two electron discharge devices are employed, one indicated as a dash tube 22 which is responsive to dash signals for controlling the stepping magnet I0 and the restoring magnet il through theintermediary of relays 25 and 24, respectively, and the other indicated as a space tube 23 which is responsiveto'spaces of predetermined length for controlling the restoring magnet through a relay 26 in the anode circuit of the space tube.

In addition, a locking relay 21 is provided which is operated through the contacts of stepping magnet I0 upon receipt of the correct signal 'composed oi the regular series of three dashes separated by spaces under one and one-half seconds. This relay is arranged to lock up after actuation in order to give a steady alarm until such time as reset key 42 is manually operated to restore the system to normal. There is thus obtained a continuous alarm indication which functions to attract the attention of the attendant until the circuit is set at rest. Another feature of the circuit of Figure 2 is the contact arrangement 28, 29 which is mechanically connected to the armature 34 of the stepping magnet I0 whereby both the 'restoring magnet and the space tube 23 do not become effective until after the armature of the stepping magnet has advanced at least one notch or step. 'I'his contact device is arranged to be normally open and to prepare the circuits through the restoring magnet coil and the cathode of the space tube for closure only after the actuation of the stepping magnet armature.

In this embodiment, the electrostatic timing circuits include two resistance-capacity circuits 30 and 3| for controlling the action of the tubes 22 and 23.

In the operation of the circuit of Figure 2, signals incoming from the radio receiver actuate signal relay 33 which is preferably connected in' the anode circuit of the radio receiver, not shown. The operation of relay-33 will close a circuit to energize the condenser C4 of resistance capacity circuit 30 over a path which may be traced from the positive side of source 2| through the make contact and armature of relay 33 to one plate of the condenser and from the other plate of the condenser to the negative side of source 2|, thus permitting a charge to accumulate on the condenser. Circuit 30 is s0 arranged that the full charge on condenser C4 is not obtained until after a lapse of three and one-half seconds, at which time there will be a suicient charge to permit dash tube 22, which has its control grid connected to the condenser,to pass sufficient current in its anode circuit to operate the three and one-half second dash relay 25. In this connection it should be noted that although dash tube 22 permits current to flow in its anode circuit immediately upon the application of a positive charge from condenser C4 there will not be sulcient current in its anode circuit to actuate relay 25 until the full charge from condenser C4 is applied to the control grid, a matter which will not occur until the condenser has been charged for a full three and one-half seconds. 'I'he operation of relay 25 in the anode cathode circuit of tube 22 will complete a path to operate stepping magnet Ill and thus move its armature one n otch or step, over a circuit which may be traced from the positive side of source 2|, the armature and break contact of relay 24, winding of stepping magnet |0, armature and make contact 43 of relay 25 to the negative side of source 2|. Although relay 24 is serially connected with relay 25 5 in the anode cathode circuit of tube 22, this relay does not operate at this time since itis arranged by means of the tension on the spring of its amature not to operate until a dash of four and one-half seconds duration or longer has 10 been received. If the incoming signal persists for four and one-hall' seconds or longer, relay 24 in the anode circuit of dash tube 22 will operate, thus breaking the circuit for stepping magnet I and closing a circuit to energize restore magnet I 15 and thus set the stepping magnet III and the entire system back at normal or start position. This latter circuit may be traced from the positive terminal oi source 2|, armature and make contact of the four and one-half seconds dash 20 relay 24, winding of restore magnet contact 23, which will be made since the stepping magnet has already advanced its armature one notch, to the negative terminal ofsource 2 If the ilrst dash has a duration between three 25 and one-half and four and one-half seconds and is followed by a space signal, relay 33 will i'all back to its normal position, closing an obvious circuit to discharge condenser C4 of the resistance capacity circuit 340. Relay 25 will then return to U0 normal, opening make contact 43 and closing break contact 45. If the space vdoes not exceed one and one-half seconds and is followed by another dash, relays 33 and 25, together with dash tube 22, will again function in precisely the same 35 manner described above and stepping magnet I0 will move its armature another notch forward. However, if the space following the dash has a duration of more than one and one-half seconds, then there will be involved a total length of time 40 for the second dash and the rst space which will be more than ve seconds, i. e., a dash of three and one-half seconds plus a space of at least one and one-half seconds. 'Ihis length of time is sufllcient to enable resistance capacity circuit 3| 45 to build up a charge on its condenser Cs which is suillcient to cause current to flow in the anode circuit of space tube 23 in which there is serially connected a relay 26 which, when operated, closes a circuit to energize restore magnet More 50 specifically, there is provided a space grid relay 32 which controls the operation of space tube 23 for Arestoring the system upon the receipt of a space of more than one and one-half seconds duration. This space grid relay is arranged so 55 that in its normal or unenergized position the condenser C5 in resistance-capacity circuit 3| is closed through the armature and make contact of the relay through resistor Rz to the positive side of source 2|, the other plate of the condenser (50 being connected to the cathode circuit of tube 23. The cathode circuit, it should be remembered, is not closed through to the negative side of source 2| until contact 29 has been closed, which occurs when the stepping magnet has advanced at least 65 one notch. The unenergized position of relay 32 for ve seconds or over enables a charge on condenser Cs to build up to a value which is suihcient to permit current to flow through the space tube 23 for operating relay 26 in the anode circuit of 70 the tube which, in turn, controls the operation of restoring magnet Relay 32, it will be noted, is in parallel relationship with stepping magnet Il) and will operate therewith. The operation of this relay short circuits the condenser of circuit 75 3| and discharges same, disconnecting the left hand plate of condenser C5 from the positive terminal of source 2|. will be evident that as long as the rst space and the second dash are completed before ve seconds have elapsed the condenser oi' resistancecapacity circuit 3| will not have an opportunity to cause the operation of relay 25 in the anode circuit of space tube 23, and stepping magnet I0 will be permitted to move up to the next step.

At the end of three correct dashes the armature of the stepping magnet I 0 will have moved up to the third segment, and in this position will connect this segment to the metallic arcuate shaped segment 4|) which is in circuit with one sideilof the locking ringing relay 21. Then if the third dash is followed by any space at all, relay 25 will return to normal and close this side of ringing relay 21 to the positive terminal of source 2|, thus completing the path to operate relay 21. I'his path is traced from the negative terminal of source 2| to one side of relay 21 and from the other side of relay 21 through arcuate element 4|) and the third contact segment of the stepping magnet, through normal make contact of relay 25 and the windings of the stepping magnetv I3 and space grid relay 32 in parallel and through the normal make contacts of relay 24 to the positive terminal or source 2|. Since the current through the ringing relay needed for its operation is very small, the stepping magnet will not actuate its own armature mechanism further even though there is present a small amount of current flowing through its coil. Upon operating, relay 21 closes a circuit through its outer armature and outer make contact to energize alarm 4|.

When the locking ringing relay 21 is energized, its inner armature closes a path to hold the coll energized over an obvious circuit. In order to reset the mechanism after an alarm has once been registered there is provided a reset button 42 which, when pushed opens the locking circuit through the contact of the button, and closes another contact 44 for energizing the restoring magnet and setting the circuit at rest.

It will be apparent from what has been said before that ordinary telegraphic dots and dashes do not permit charges to gradually build up on the condenser circuit, since this is prevented by means ol' the discharge contacts on the signal relay 33 and the space charge relay 32 which provide shunt paths for their respective condensers each time the relays function normally in the ordinary cycle of operations. The use of such an electrostatic time constant circuit permits very fast recycling of the operations of the system merely by the discharging of the condenser.

Another time constant circuit arrangement which may be used for obtaining a. time delay instead of the electrostatic resistance condenser combination is the resistance inductance scheme shown in Figure 3. In this case when the current through the resistor R has reached a suitable value after a time delay due to the presence of inductance in the circuit, current of a desired value will ow through the anode circuit of the electron discharge device and actuate the relay.

The embodiments of the invention illustrated and described herein have been selected for the purpose of clearly setting forth the principles involved. It will be understood, however, that the invention is susceptible of being modied to provide various values of timing and to meet difierent conditions encountered in its use, and it is, therefore, aimed to cover by the appended claims From the foregoing, itv

all modications within the spirit and scope of the invention.

I claim: A

1. An automatic selector circuit varrangement 5 having, in combination, a signal relay responsive to incoming signal impulses, an electron discharge device, input and output circuits for said device, a time constant circuit including a resistor and a reactance in said input circuit, said time constant circuit being arranged upon the application of potential thereto under control of said signal relay to permit said electron discharge device to pass a predetermined amount of current after a certain time delay, a relay in said output circuit responsive to said ow of current through said device, an indicator, an actuating device under control of said last relay for rendering operative said indicator, and a delayed action relay in series with said rst relay and operative by the current in said output circuit on the reception of an impulse of a certain duration for rendering said actuating device inoperative.

2. An automatic selector circuit arrangement having, in combination, a signal relay responsive to incoming signal impulses, a thermionic device, input and output circuits for said device, a time constant circuit including a condenser and a resistor in said input circuit, the charge on said condenser being controlled by said signal relay in accordance with received signal impulses, said time constant circuit when charged being arranged to permit said thermionic device to pass current, a relay in said output circuit operative by the current through said device on the reception of an impulse of a certain duration, an indicator, an actuating device under control of said last relay for rendering operative said indicator, and a delayed action relay operative by the current in said output circuit on the reception of an im- 40 pulse of a different duration for rendering said actuating device inoperative.

3. An automatic selector circuit arrangement having, in combination, a signal relay responsive to incoming signal impulses, an electron dis- 45 charge device, input and output circuits for said device, a time constant circuit including a resistor and a reactance in said input circuit, said time constant circuit being arranged upon the application of potential thereto under control of 50 said signal relay to permit said electron discharge device to pass a predetermined amount of current only after said signal relay has been operated continuously for a certain interval of time, av

relay in said output circuit responsive to said iiow of current through said device, an indicator, a step-by-step switch and a motor magnet therefor repeatedly operable in accordance with impulses fed thereto by the last said relay, said indicator being operable only after said magnet has advanced said step-by-step switch a plurality of steps, another electron discharge device having an operating path under control of the last said relay, delay means connected between the last said electron discharge device and the last said relay for causing current to flow through said electron discharge device when said relay remains de-energized for at least a predetermined interval of time and means connected in the output circuit of the last said electron discharge device for rendering said motor magnet inoperative.

sistor and Ia reactance in said input circuit, said time constant circuit being arranged upon the application of potential thereto under control of said signal relay to permit said electron discharge device to pass a predetermined amount of current after a certain time delay, a relay in said output circuit responsive to said ow of current through said device, an indicator, an actuating device comprising a step-by-step switch and a magnet therefor under control of said last relay for rendering operative said indicator after the switch has been advanced at least three steps by said magnet, and another relay in series with said last relay and responsive to the ow of current in said output circuit for a time interval different than said rst time interval for rendering said actuating device inoperative and for restoring said step-by-step switch to normal.

5. An automatic selector circuit arrangement having, in combination, a signal relay, a thermionic device, input and output circuits for said device, a time constant circuit including a condenser and a resistor in said input circuit, the charge on said condenser being controlled by said signal relay in accordance with received signal characters, said time constant circuit when charged being arranged' to permit said thermionic device to pass current, a delayed action relay in said output circuit operative by the current through said device on the reception of an lmpulse of' a certain duration, an indicator, an actuating device under control of said last relay for rendering operative said indicator, a second.

delayed action relay in series with said irst delayed action relay and operative by the current through said thermionic device upon reception of an impulse of a different duration for rendering said actuating device inoperative, and a second thermionic device having an input and an output circuit, the operating path of said second device being closed only subsequent to the operation of said actuating device at least once, and a relay in said last output circuit for restoring said actuating device, another time constant circuit connected to the input of said second device, and means for charging said last time constant circuit during spaces of predetermined duration between signal impulses to cause said second thermionic device to pass current whereby the relay in its output circuit is operated and s aid actuating device restored to normal.

6. In combination, an electron discharge device having an anode, a cathode and a control electrode, means for biasing said control electrode negatively with respect to said cathode, a condenser in circuit with said control electrode, a signal relay responsive to signal impulses for charging said condenser, said condenser being designed when charged to overcome the bias on said control electrode for enabling current to pass through said device, an electromagnetic relay connected to said anode and responsive to a predetermined amount of current now through said device, a step-by-step switch having at least three position steps and a stepping magnet responsive to each operation of said electromagnetic relay for advancing said switch one step at a time, an indicating arrangement responsive to the movement of said switch at least to the third step for giving an alarm, a restoring magnet for said switch and another electromagnetic relay operable under control of said electron discharge device when the latter remains conductive for a predetermined interval of time, due to the continued operation of said signal relay, for energizing said restoring magnet to restore said switch to normal.

7. In combination, an electron discharge device having an anode, a cathode and a control electrode, means for'biasing said control electrode negatively with respect to said cathode, a condenser in circuit with said control electrode, a signal relay responsive to signal impulses for charging said condenser, said condenser being designed when charged to overcome the bias on said control electrode for enabling current to pass through said device, an electromagnetic relay connected to said anode and responsive to a predetermined amount of current flow through said device, a step-by-step switch having at least three position steps and a stepping magnet responsive to each operation of said electromagnetic relay for advancing said switch one step at a time, an indicating arrangement responsive to the movementr of said switch at least to the third step to give an alarm, and a. normally opened contacting mechanism mechanically linked to said switch and closing in response to movement of said switch from its normal position, and another relay responsive to the absence of signals for a predetermined interval of time for energizing said restoring magnet to restore said step-bystep switch to normal, the closure of said contacting mechanism functioning to complete the operating path of said last relay.

8. An automatic selector circuit arrangement having, in combination, a signal relay responsive to incoming signal impulses, a thermionic device, input and output circuits for said device, a time constant circuit including a condenser and a resistor in said input circuit, the charge on said condenser being controlled by said signal relay in accordance with received signal impulsessaid vtime constant circuit, when charged, being ar ranged to permit said'thermionic device to pass current, a relay in said output circuit operative by the current through said device on the reception of an impulse of a certain duration, an indicator, an actuating device movable step-by-step irom'a normal position under control of said last relay for rendering operative said indicator, a second thermionic device, input and output circuits !or said last device and a time constant circuit also in said last input circuit, a relay in said last output circuit, said second thermionic device and said last relay constituting means responsive to space signals of predetermined duration between successive time intervals for rendering said actuating device inoperative, and being operative only subsequent to the movement of said actuating devic'e from its normal position.

9. In combination, an electron discharge device having an anode, a cathode and a control electrode, means for biasing said control electrode negatively with respect to said cathode, a condenser in circuit with said control electrode, a signal relay responsive to signal impulses for charging said condenser, said condenser being designed, when charged, to overcome the bias on said control electrode for enabling current to pass through said device, an electromagnetic relay connected to said anode and responsive to a predetermined amount of current ilow through said device, a step-by-step switch having at least three position steps and a stepping magnet responsive to `each operation of said electromagnetic relay for advancing said switch one step at a time, an indicating arrangement responsive to the movement of said switch at least to the third step to give an alarm, and a normally opened contacting mechanism mechanically linked to said switch and closing in response to movement of said switch from its normal position, and another relay operative by the current through said device on the reception of an impulse of a certain duration for energizing said restoring magnet to restore said step-by-step switch to normal, the closure of said contacting mechanism functioning to complete the operating path oi' said restoring magnet.

10. An automatic selector circuit arrangement having in combination, a signal-responsive relay, a thermionic device, input and output circuits for said device, said input circuit including a condenser-resistor combination constituting means under control of said signalresponsive relay for producing a retarded response to signals, said response constituting a ilow of current in said thermionic device, a second relay in said output circuit adapted to be energized by current through said thermionic device, an indicator, an indicator actuating device operable under control of said second relay, a second thermionic device having an input and an output circuit, said input circuit including a second condenserresistor combination constituting means under control oi said second relay when it de-energizes for producing a retarded response constituting a ilow of current in the output circuit of said second thermionic device, and a third relay operable by current ilow in the output circuit of said second thermionic device for rendering said actuating device inoperative only upon the occurrence of spacing signals of a predetermined minimum duration.

` IRVING F. BYRNES. 

